The LockheedC-5 Galaxy, one of the largest military transport aircraft ever built, is known not only for its sheer size and incredible cargo capacity, but also for a sound that is instantly recognizable. Long before the aircraft comes into view, its presence is announced by a haunting, rising whine that builds into a powerful, almost unsettling howl. For aviation enthusiasts, that sound is iconic. For casual observers, it is often confusing, even alarming, as it bears little resemblance to the noise produced by modern commercial planes.